Capacitive touch screens have been widely used in mobile handheld electronic devices. The capacitive touch screen includes a display screen with a transparent capacitive touch panel disposed thereon. In current product design and fabrication, almost all capacitive touch screens adopt the similar circuits and structures. As shown in FIG. 1, from the perspective of circuit logic principle, the touch panel is usually a module integrating a capacitive touch sensor and a touch controller. The touch controller detects touches on the capacitive touch sensor, and transmits a detection result to a host circuit board. As shown in FIG. 2, from the perspective of structure, the touch panel is connected to the host circuit board of the electronic device through a flexible printed circuit (FPC) board, and the touch controller is installed on the FPC board. According to the capacitive touch detection principle, to obtain satisfied detection results, various characteristic parameters of the capacitive touch sensor that is used in combination with the touch controller need to be preset in the touch controller prior to the touch detection. Considering the characteristics of the capacitive touch detection technology, in this type of application, the touch controller and the capacitive touch sensor that is used have a one-to-one correspondence relationship. That is, each specific capacitive touch sensor needs to be used in combination with one specific touch controller model and corresponding firmware.
However, during mass production, for the purposes of simplifying the fabrication process and controlling the procurement cost, the manufacturers often wish to install the touch controller on the host circuit board, and wish that the same touch product can use touch sensor modules without a touch controller that are of different models or are supplied by different suppliers. What is needed, therefore, is to enable the touch controller installed on the host circuit board to identify the touch sensors of different models or supplied from different suppliers, such that the touch controller is able to automatically use preset parameters corresponding to the specific touch sensor to thereby obtain ideal touch detection results. FIG. 3 illustrates a conventional method for addressing this issue. In FIG. 3, part of IO ports in the layout of the touch controller are defined as model selection input pins P1, P2, . . . , P6, and are connected to different combinations of high and low voltage through a simple switch circuit K1, K2, . . . , K6. This way, the touch controller is enabled to select corresponding touch sensor model according to the input status of these selection input pins. However, this method has the disadvantages that it needs to occupy the IO ports of the touch controller and multiple pins on the FPC need also to be occupied. The IO ports of the touch controller are often scarce resources and increasing the number of the FPC pins also increases the cost of connectors. This may be why this method has never been widely put into practice. What is needed, therefore, is a better method for addressing this issue.